workpackage n° 4 1 nanospad review meeting brussels, may 6 2008 full title: single photon avalanche...
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Nanospad Review meeting Brussels, May 6 2008Workpackage N° 4 1
Full Title: Single Photon Avalanche Diode (SPAD) per la lettura di Fibre Scintillanti
Bando ASI per lo Sviluppo Tecnologico Coordinating person: Piera Maccagnani Partecipants: CNR-IMM, INAF-IASF Bologna, Poli-MI, Micro Photon Devices, Finanziamento richiesto: 300 k€ per 24 mesi Stato: ammesso al finanziamento Data di inizio: ????
FIBER-SPAD PROJECT
Attività: • realizzare rivelatori SPAD a grande area attiva (diametro di almeno 500m) da
interfacciare con fibre scintillanti. • progetto e realizzazione dell’elettronica non standard di acquisizione ed
elaborazione del segnale. • test delle prestazioni del sistema complessivo con sorgenti e fasci di particelle.
Obiettivo: realizzazione di un rivelatore per raggi gamma basato su fibre scintillanti con lettura mediante Single Photon Avalanche Diode (SPAD).
Nanospad Review meeting Brussels, May 6 2008Workpackage N° 4 2
Full Title: Protein microarray for enhanced diagnostics at low cost by integration of new technological developments
6FP – STREP Thematic Priority: IST-NMP-2 Bio-sensors for Diagnostic and Healthcare Coordinating person: Prof. Sergio Cova (MPD) Partecipants: Poli-MI, CNR-IMM e ICRM, CNRS, Univ. College Cork, Paul-Erlich
Institut, Univ. Claude Bernard Lyon1 Finanziamento: 310 k€ per 30 mesi, 60 man months Durata: 1/12/2005 – 31/5/2009
NanoSPAD PROJECT
Obiettivo: sviluppare uno strumento compatto per una diagnosi rapida e a basso costo delle allergie, basato su un micro-array biologico e su una matrice di rivelatori SPAD
Attività IMM-BO: sviluppare una matrice di rivelatori SPAD da interfacciare al micro-array biologico (WP4)
Nanospad Review meeting Brussels, May 6 2008Workpackage N° 4 3
Final objective: To develop a To develop a compact compact apparatusapparatus that can efficiently that can efficiently detect and measure arraysdetect and measure arrays of of proteins labeled with proteins labeled with luminescent probes.luminescent probes.The apparatus will employ a The apparatus will employ a matrix of single-photon matrix of single-photon detectorsdetectors (typically 48 (typically 48 detectors).detectors).Each element of the matrix is Each element of the matrix is intended to measure the intended to measure the emission intensity from one of emission intensity from one of the micro-spots of the protein the micro-spots of the protein microarray.microarray.
NanoSPAD PROJECT
Nanospad Review meeting Brussels, May 6 2008Workpackage N° 4 4
Basic concept: use of an Array detector
Target application:
“in-vitro” allergy diagnosis with
chemiluminescent protein microarray
Optical implementation:
Each spot of the microarray is conjugated to a SPAD pixel through a 1:1 imaging optics
Nanospad Review meeting Brussels, May 6 2008Workpackage N° 4 5
WP4 - Development of monolithic arrays of SPADsDevelopment of monolithic arrays of SPADs
Matrix of SPAD detectors with wide pixel area 2x3mm2 matrices with 48 SPAD elements, 240 m pitch matrix pixels with active area diameter of 50m matrix geometry conjugated to that of the allergen microarray good performances obtained for single pixel-SPAD good SPAD performance uniformity inside the matrix
4 interleaved sectors including 12 pixels with common anode
sector 1
sector 2
sector 3
sector 4
Nanospad Review meeting Brussels, May 6 2008Workpackage N° 4 6
Detector noise sources:
• Thermal Carrier Generation (Dark Counting Rate, DCR)
• Carrier Trapping and Delayed Release (Afterpulsing effect)
Reducing the Detector NoiseReducing the Detector Noise
For achieving low noise:
Good quality substrates
Clean processing
Efficient GETTERING
Reduced electric field
Nanospad Review meeting Brussels, May 6 2008Workpackage N° 4 7
Improved Technological SPAD process
isolfield
active
xx
metal
• Implant to realize the p+ doped region• Process to oxidize the SPAD active area• Gettering processes• Different cleaning during technological process
Nanospad Review meeting Brussels, May 6 2008Workpackage N° 4 8
Effect of Effect of CLEANINGCLEANING processes processesMain characteristic processes:• active area oxidation• doping of p+ regions• defects gettering• process cleaning
• Uniform reduction of DCR @Tamb (21°C)
• Best DC reduced of 50%
• Plasma cleaning introduces defects in the SPAD active area.
Nanospad Review meeting Brussels, May 6 2008Workpackage N° 4 9
Effect of Effect of IMPLANTIMPLANT process for p process for p++ regions regions
• Uniform reduction of DCR @Tamb (21°C) 5 times
• Implanting BF2 we introduce defects in the SPAD active area. Probably due to Mo contamination.
Main characteristic processes:• active area oxidation• doping of p+ regions• defects gettering• process cleaning
Nanospad Review meeting Brussels, May 6 2008Workpackage N° 4 10
Effect of Effect of OXIDATIONOXIDATION process process
• Same trend for the 2 oxides
• Same DC low level @Tamb
• LTO shows lower % of “good” devices
Main characteristic processes:• active area oxidation• doping of p+ regions • defects gettering• process cleaning
Nanospad Review meeting Brussels, May 6 2008Workpackage N° 4 11
Effect of Effect of GETTERINGGETTERING process process
• Same trend and behaviour of DC @Tamb
• NO CLEAR effect of the gettering process
Main characteristic processes:• active area oxidation• doping of p+ regions• defects gettering• process cleaning
Nanospad Review meeting Brussels, May 6 2008Workpackage N° 4 12
OLDOLD vs vs NEWNEW Process Flow Process Flow
• Higher % of devices with DCR<1kc/s @21°C:44% in NEW Run vs 10% in the OLD Run
• NEW Run Best devices with 300-500 counts/s vs 700-1000c/s from OLD Run
Selected processes:• Thermal oxidation• Boron doping of p+ regions • Long gettering (5h)• Wet cleaning
Nanospad Review meeting Brussels, May 6 2008Workpackage N° 4 13
OLDOLD vs vs NEWNEW Process: large area SPAD Process: large area SPAD
• lower DCR confirmed also for 100m SPAD
• Higher % of devices with DCR<5kc/s @21°C:26% in NEW Run vs 7% for OLD Run
• NEW Run Best devices with a thousand counts/s vs thousands counts/s in the OLD Run
Nanospad Review meeting Brussels, May 6 2008Workpackage N° 4 14
Wafer distribution map
• Full wafer characterization:300 SPAD - 50m600 SPAD - 100m
• Confirmed good fabrication yield for 50 and 100m single SPAD
• Good uniformity in VBD values distribution: VBD=36.1V ± 0.5V
• Low detector noise:< 1kc/s for 45% of 50m SPAD< 10kc/s for 70% of 50m and 40% of 100m SPAD< 100kc/s up to 200m SPAD
Pass SPAD8 S8-3 TEST AVGVBD %y
37.1936.7036.2135.7235.2334.7434.25
detection limit is not imposed by DCR of the detector NO COOLING required
Nanospad Review meeting Brussels, May 6 2008Workpackage N° 4 15
6x8 SPAD matrix detector6x8 SPAD matrix detector
• 50 µm pixel diameter
• 240 µm pitch
• 4 interleaved sectors including 12 pixels with common anode
sector 1
sector 2
sector 3
sector 4
Nanospad Review meeting Brussels, May 6 2008Workpackage N° 4 16
Matrix Breakdown Voltage distributionMatrix Breakdown Voltage distribution
All 48 pixels commonly working no blind zone in the matrix
• Good process control:new run: 36.2V ± 23mVold run: 37.9V ± 34mV
• Good uniformity obtained in: Photon detection efficiency Series resistance
Nanospad Review meeting Brussels, May 6 2008Workpackage N° 4 17
Matrix Dark Counting Rate (DCR)Matrix Dark Counting Rate (DCR)
Percentage of individual SPAD elements (horizontal scale) found within a given limit of the individual dark counting rate (vertical scale) measured for old and new SPAD matrix.
Reduced DCR level confirmed also for the 50m SPAD in the matrix:
42% pixels with DCR<1 kc/s 90% pixels with DCR< 10kc/s
NO COOLING required for matrix operation in NanoSPAD project
Nanospad Review meeting Brussels, May 6 2008Workpackage N° 4 18
Dark Counting Rate vs TemperatureDark Counting Rate vs Temperature
Dark count: combined effect of band-to-band tunneling (dotted line) and SRH generation (dashed line). The two contributions equals ~ -10°C
• reduced band-to-band contribution due to engineered profile for electric field
→ better DC reduction lowering temperature
• very low DCR even @ 20°C
due to cleanup and gettering
processes in the active region
• Afterpulsing
No AP @ 20°C with tH=250ns
AP=1% @ 20°C with tH=70ns
AP=1.5% @ -15°C tH=70ns
Nanospad Review meeting Brussels, May 6 2008Workpackage N° 4 19
Matrix Photon Detection EfficiencyMatrix Photon Detection Efficiency
4% PDE spreading @530nm
inside matrix (48 pixels)
• lower PDE value:
@530nm 48-52% old
vs 44-48% new
Reduced thickness for the coating
SiO2 layer
New run:• PDE max = 48% @530nm• PDE > 30% over visible range
Nanospad Review meeting Brussels, May 6 2008Workpackage N° 4 20
Matrix PDE and Luminol SpectrumMatrix PDE and Luminol Spectrum
Luminol emission peak= 445nm
SPAD PDE@445nm = 35÷38%
quite good value
Spectrum of chemiluminescence emitted following the catalysis of the reaction by the label.
Nanospad Review meeting Brussels, May 6 2008Workpackage N° 4 21
WP4: Achievements – problems – further actions
Achievements: Good performance SPAD matrices with 48 elements obtained in shorter time than
planned (24 months instead of 30 months)
Development of a NEW Process Flow for advanced SPAD devices: Improved performances obtained for single SPAD devices with 50m diameter
and for monolithic SPAD matrix with 48 detectors: low operating voltage: ~ 36V very uniform matrix breakdown voltage uniform PDE PDE >30% in the spectral range 500 – 700nm very low and uniform dark counting rate: ≤1kc/s for 45% matrix pixels
no cooling required for matrix operation low afterpulsing effect: ~ 1% @ 20°C with tH=70ns reduced band-to-band tunneling due to low electric field profile
better DC reduction at low temperature operation
Nanospad Review meeting Brussels, May 6 2008Workpackage N° 4 22